Hmmm, I can try playing with this once I'm home (no touchpads in front of me here), but what happens if you set MinSpeed and MaxSpeed to 0? Does that make the pointer not move? Alternatively, what if you use xinput to float the device (though maybe that'll break scrolling)?
–
derobertOct 19 '12 at 18:27

@derobert: that didn't work, but put me on the right track.
–
mattdmOct 22 '12 at 3:06

I find middle-click scrolling pretty convenient, but I'd love to use the touch pad for pinch-zooming, and the mouse buttons for nav-forward and -back. (This will likely be my last Lenovo, because they've messed with the keyboard layout, and those and other keys are missing. :-( )
–
Michael ScheperFeb 21 at 5:41

2) Set the left and right "edges" of the trackpad to be 0. They default to being some value in the thousands, making a little border. Use xinput --list-props to find the initial values — the 4282 value for the bottom edge comes from that. I've also set the top edge to 0, on the grounds that that doesn't hurt.

Awesome answer, but I find I do still trigger it accidentally—I have big hands, I suppose. I'd love it to scroll only when I use two fingers, and for other multi-finger features, like pinch zooming, to work too.
–
Michael ScheperFeb 21 at 5:46